Polk Audio TSi100 Bookshelf Speakers (Pair) With A Polk Audio CS10 Center Channel Speaker Bundle! TSI100: Equipped with one 5.25-inch dynamic balance bilaminate composite woofer / Equipped with one 1-inch silk/polymer composite dynamic balance dome tweeters TSI100: Frequency response: 53Hz - 25kHz / Recommended amplification: 20-100 (watts/ch) CS10: Center channel speaker in black; recommended amplification of 20-125 watts/channel CS10: Equipped with two 5.25-inch diameter bi-laminate organic fiber cone woofers; 1-inch silk/polymer composite Dynamic Balance dome tweeter